An approach to manipulate frequency selectivity in Basilar metamembrane based broadband frequency sensors

Abstract

Basilar metamembrane (BM2) based frequency sensors have received growing interest in the engineering community for its ability to control the sensing/analyzing broadband frequency spectrum while mimicking the geometry and functionality of a basilar membrane (BM) in mammalian cochlea. Membrane stiffness plays the principal role in spatial selection of acoustic frequencies in BM2. Likewise natural BM, conventional BM2 possess homogeneous stiffness over the membrane length. However, broadband frequency selection ability of the BM2's are considerably less due to geometric simplicity adopted in BM2's (uniform thickness) compared to BM (tapered thickness). This work presents the possibility to manipulate (increase/decrease) the broadband frequency selection ability of the sensor, using functionally graded membrane stiffness. Three popular functions (logarithmic, exponential and linear) are presented as potential expression to grade membrane stiffness. A detailed insight is provided, how sensing parameters of a specific frequency band (e.g. sensing location of band start and end frequency, membrane segment width necessary to sense whole frequency band) can be influenced by coefficients of the functions.